feat: add npc info (level and aggro radius)

Client/Application/Converters/CenterOfParentConverter.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+
+namespace Client.Application.Converters
+{
+    public class CenterOfParentConverter : IMultiValueConverter
+    {
+        public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+        {
+            return (double)values[0] + (double)values[2] / 2 - (double)values[1] / 2;
+        }
+
+        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}